U.S. patent application number 14/325856 was filed with the patent office on 2015-01-08 for pump.
The applicant listed for this patent is MAGNA POWERTRAIN BAD HOMBURG GMBH. Invention is credited to Ludger Holtmann, Kerstin Rosenkranz.
Application Number | 20150010419 14/325856 |
Document ID | / |
Family ID | 52106497 |
Filed Date | 2015-01-08 |
United States Patent
Application |
20150010419 |
Kind Code |
A1 |
Holtmann; Ludger ; et
al. |
January 8, 2015 |
PUMP
Abstract
A pump has a suction region, a pressure region, and a pressure
space which has an outflow region. A rotor is connected to a shaft
in which rotor delivery elements are displacably received. The
rotor has expelling regions connected to the pressure region by way
of a first fluid path. A cold starting device is prestressed into a
first functional position to shutoff a second fluid path from the
pressure region to the pressure space, and is configured to be
displaced counter to the prestress into a second functional
position to open the second fluid path. The cold starting device is
arranged in its second functional position at least in regions with
a relief face which faces away from the pressure region in a relief
receptacle. The relief face is loaded during operation of the pump
with a pressure being smaller than a system pressure in the outflow
region.
Inventors: |
Holtmann; Ludger;
(Hohenlinden, DE) ; Rosenkranz; Kerstin;
(Oberursel, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAGNA POWERTRAIN BAD HOMBURG GMBH |
Bad Homburg |
|
DE |
|
|
Family ID: |
52106497 |
Appl. No.: |
14/325856 |
Filed: |
July 8, 2014 |
Current U.S.
Class: |
418/135 |
Current CPC
Class: |
F04C 14/06 20130101;
F04C 2/30 20130101; F04C 15/0023 20130101; F04C 18/344 20130101;
F04C 2270/701 20130101; F04C 2/344 20130101 |
Class at
Publication: |
418/135 |
International
Class: |
F04C 14/06 20060101
F04C014/06; F04C 2/30 20060101 F04C002/30; F04C 15/00 20060101
F04C015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 8, 2013 |
DE |
102013107176.7 |
Claims
1. A pump comprising: at least one suction region and at least one
pressure region; a pressure space which has an outflow region to a
consumer; a rotor which is operatively connected to a shaft which
rotates about a rotational axis, in which rotor delivery elements
are received displaceably, as viewed in the radial direction; the
rotor having expelling regions radially within the delivery
elements, which expelling regions are connected at least partially
to the pressure region by way of a first fluid path; and a cold
starting device which comprises a cold starting element which is
prestressed into a first functional position and, in its first
functional position, shuts off a second fluid path from the
pressure region to the pressure space, the cold starting element
opening the second fluid path in a second functional position, the
cold starting element being configured and arranged in such a way
that it can be displaced counter to the prestress into its second
functional position by way of a pump pressure which is generated in
the pressure region during operation of the pump; wherein the cold
starting element is arranged in its second functional position at
least in regions with a relief face which faces away from the
pressure region in a relief receptacle in such a way that the
relief face is loaded during operation of the pump with a pressure
which is smaller than a system pressure in the outflow region.
2. A pump according to claim 1, wherein the cold starting element
is configured as a cold starting plate, the cold starting plate
preferably being prestressed into its first functional position by
way of a spring element.
3. A pump according to claim 1, wherein the relief receptacle is
configured as a bore, preferably in a housing of the pump.
4. A pump according to claim 1, wherein a relief bore opens into
the relief receptacle, which relief bore is fluidically connected
to a surrounding area of the pump or to a reservoir for a fluid
which is delivered by the pump.
5. A pump according to claim 4, wherein the relief receptacle has
an axial bottom face, the relief bore opening into the axial bottom
face, and the relief face being arranged in the first functional
position at a first spacing and in the second functional position
at a second spacing from the axial bottom face, the second spacing
being smaller than the first spacing.
6. A pump according to claim 1, wherein, on a wall which reaches
around the relief receptacle, the relief receptacle has an axial
end face which is preferably configured as an annular face and on
which a first sealing element is arranged, against which the cold
starting element bears sealingly with a rear face in the second
functional position.
7. A pump according to claim 1, wherein, on its side which faces
away from the pressure region, the cold starting element has a
relief projection, on which the relief face is arranged, the relief
projection being guided displaceably in the relief receptacle.
8. A pump according to claim 7, wherein the relief projection is
guided with play in the relief receptacle.
9. A pump according to claim 7, wherein the relief projection is of
spherical configuration.
10. A pump according to claim 7, wherein the relief face which is
arranged on the relief projection is reached around by a second
sealing element, by way of which the relief projection bears
sealingly against the axial bottom face in the second functional
position.
11. A pump according to claim 7, wherein a third sealing element is
arranged on the relief projection, which third sealing element
reaches around the relief projection, as viewed along its
circumference, the third sealing element bearing sealingly against
a wall which reaches around the relief receptacle.
12. A pump according to claim 7, wherein the relief projection is
guided substantially without play in the relief receptacle.
13. A pump according to claim 7, wherein, on a circumferential
face, the relief projection has at least one pressure relief groove
which extends in the circumferential direction.
14. A pump according to claim 1, wherein the cold starting element
is configured overall as a piston which is guided in regions in the
relief receptacle.
15. A pump according to claim 14, wherein a fourth sealing element
is arranged on a stop face of the cold starting element, which stop
face faces the axial bottom face, the cold starting element bearing
sealingly with the fourth sealing element against the axial bottom
face in its second functional position.
Description
RELATED APPLICATION
[0001] The subject application claims priority to DE
102013107176.7, filed on Jul. 8, 2013, and entitled a "Pump", the
entire disclosure of which is incorporated herein by reference.
FIELD
[0002] The present disclosure relates to a pump having at least one
suction region and at least one pressure region.
BACKGROUND
[0003] This section provides background information related to the
present disclosure that is not necessarily prior art.
[0004] A pump which has two pump sections with in each case one
suction region and in each case one pressure region is apparent
from European Patent Application EP 0 758 716 A2. A pressure space
with an outflow region to a consumer is provided, the pump
delivering, during its operation, a fluid from the suction regions
into the pressure space and via the outflow region further to a
consumer. The pump has a rotor which is operatively connected to a
shaft which can be rotated about a rotational axis. Delivery
elements are received displaceably, as viewed in the radial
direction, in the rotor, the delivery elements being configured as
vanes, with the result that the known pump overall is configured as
a vane cell pump. The function of the pump is configured in such a
way that the rotor rotates within a contour ring during operation,
driven by the shaft, two crescent-shaped delivery spaces being
formed by it, which are passed through by the delivery elements
which can be displaced in the radial direction. This results during
the rotation of the rotor in spaces which become larger and
smaller, namely the suction and pressure regions. Radially within
the delivery elements, the rotor has expelling regions which are
connected at least partially to at least one pressure region via a
first fluid path. In the vane cell pump, for example, lower vane
grooves are provided, by way of which the expelling regions are
fluidically connected to at least one pressure region, in order to
expel the vanes during starting of the pump. During operation of
the pump, the delivery elements are driven radially to the outside
not only by way of the centrifugal forces which act on account of
the rotor rotation, but also assisted by the pump pressure which
prevails in the expelling regions via the first fluid path, with
the result that they run sealingly on an inner circumferential face
of the contour ring. The pump is typically arranged in such a way
that its rotational axis extends substantially in the horizontal
direction. If the pump is brought to a standstill in a warm
operational state, the delivery elements which lie at the top slide
into their receptacles which are provided on the rotor on account
of gravity, as a result of which the separation which otherwise
exists between the suction and pressure region as a result of the
delivery elements is dispensed with. This produces as it were a
short-circuit in the pump section which lies at the top. The
delivery elements which lie at the bottom remain in contact with
the contour ring as a result of gravity, with the result that the
suction and the delivery region are separated here by way of the
extended delivery elements.
[0005] If the fluid which is delivered by the pump, for example a
hydraulic oil, now gets colder, its viscosity increases, with the
result that the mobility of the delivery elements decreases. If the
pump is started up, at any rate a greatly reduced delivery capacity
is produced in the case of cold starting on account of the
short-circuit in one pump section. In order to avoid this problem,
a cold starting device is provided in the pump according to
European Patent Application EP 0 758 716 A2, which cold starting
device comprises a cold starting element which is prestressed into
a first functional position, in the form of a cold starting plate.
In its first functional position, the cold starting element shuts
off a second fluid path which leads from the pressure regions to
the pressure space. At the same time, a fluidic connection between
the two pressure regions of the two pump sections is preferably
also shut off by way of the cold starting element. In a second
functional position, the cold starting element releases the second
fluid path. Here, the cold starting element is configured and
arranged in such a way that it can be displaced counter to the
prestress into its second functional position by way of a pump
pressure which is generated in the pressure regions during
operation of the pump. In the first functional position, there is
no fluidic connection between the pressure regions and the pressure
space, with the result that the fluid which is delivered by the
pump when running up is delivered completely via the first fluid
path into the expelling regions. In this way, the delivery elements
are displaced out of their receptacles which are provided on the
rotor, with the result that the short-circuit which exists at a
standstill between the suction and the pressure region is closed.
The first fluid path is particularly preferably configured in such
a way that it supplies expelling regions of this type with fluid,
which expelling regions are just moving through a suction region,
as viewed in relation to the rotation of the rotor. Therefore,
during cold starting, the pump rapidly reaches its complete
delivery capacity. If the pump pressure in the pressure regions
exceeds the prestressing force which holds the cold starting
element in its first functional position, said cold starting
element is displaced counter to the prestress into its second
functional position, with the result that it then also releases the
second fluid path which leads from the pressure regions to the
pressure space. Therefore, in the case of sufficient pump pressure,
fluid is then also delivered through the pressure space and via the
outflow region to the consumer.
[0006] It is disadvantageous here that, during the operation of the
pump, the cold starting element is constantly loaded on a side
which faces away from the pressure regions with a system pressure
which prevails in the outflow region. Two force components which
are added together therefore act on the cold starting element in
the direction of the first functional position, namely firstly the
prestressing force and secondly the force which acts on account of
the system pressure which prevails in the outflow region. These
forces have to be balanced by the pump pressure during operation of
the pump, in order to hold the cold starting element permanently in
its second functional position. The pump pressure in the at least
one pressure region therefore always has to be greater by an amount
which corresponds to the prestressing force than the system
pressure which prevails in the outflow region. This additional
pressure difference has to be applied permanently by the pump, as a
result of which said pump has an increased power consumption.
SUMMARY
[0007] This section provides a general summary of the disclosure,
and is not a comprehensive disclosure of this full scope or all of
its features, aspects or objectives.
[0008] The disclosure is based on the object of providing a pump
which does not have the stated disadvantage. In particular, a power
consumption of the pump is to be reduced with an identical delivery
capacity, it being intended for the solution to be configured so as
to save installation space and to be inexpensive.
[0009] The object is achieved by a pump, having at least one
suction region and at least one pressure region, a pressure space
which has an outflow region to a consumer, a rotor which is
operatively connected to a shaft which rotates about a rotational
axis, in which rotor delivery elements are received displaceably,
as viewed in the radial direction, the rotor having expelling
regions radially within the delivery elements, which expelling
regions are connected at least partially to the pressure region by
way of a first fluid path, and having a cold starting device which
comprises a cold starting element which is prestressed into a first
functional position and, in its first functional position, shuts
off a second fluid path from the pressure region to the pressure
space, the cold starting element opening the second fluid path in a
second functional position, the cold starting element being
configured and arranged in such a way that it can be displaced
counter to the prestress into its second functional position by way
of a pump pressure which is generated in the pressure region during
operation of the pump, wherein the cold starting element being
arranged in its second functional position at least in regions with
a relief face which faces away from the pressure region in a relief
receptacle in such a way that the relief face is loaded during
operation of the pump with a pressure which is smaller than a
system pressure in the outflow region.
[0010] By virtue of the fact that the cold starting element is
arranged in its second functional position at least in regions with
a relief face which faces away from the pressure region in a relief
receptacle in such a way that the relief face is loaded during
operation of the pump with a pressure which is smaller than the
system pressure in the outflow region, the force which displaces
the cold starting element overall into its first functional
position is reduced considerably. The cold starting element is
therefore pressure-relieved in regions, as a result of which,
during operation of the pump, lower forces and consequently a lower
pressure difference between the pump pressure and the system
pressure are necessary, in order to hold it open permanently in its
second functional position. In particular, this solution provides
that the complete face of the cold starting element, which face
faces away from the pressure region, is no longer loaded with the
system pressure, but rather that said face is relieved in regions,
by at any rate the relief face being loaded with a lower pressure.
Said lower pressure particularly preferably corresponds to an
ambient pressure of the pump, in particular an atmospheric pressure
which prevails in the surrounding area of the pump. The relief face
and the relief receptacle can be provided in the pump in a
space-saving and inexpensive manner. As a result of the pressure
relief, as has already been mentioned, the difference is reduced
between firstly the pump pressure and secondly the system pressure,
with the result that the pump has a lower power consumption with
the same delivery capacity.
[0011] One preferred exemplary embodiment of the pump is configured
as a vane cell pump. In this case, slots are made in the
circumferential wall of the rotor, which slots receive vanes
displaceably, as viewed in the radial direction. When the rotor
rotates during operation of the pump, the vanes extend out of the
slots by a distance which is predefined depending on the rotary
angle of the rotor by the contour of an inner circumferential wall
of a contour ring, in which the rotor is arranged. Here, the vanes
run on an inner circumferential face of the contour ring. By way of
the centrifugal force firstly and the pump pressure which prevails
in the expelling regions secondly, the vanes are displaced against
the inner circumferential face of the contour ring.
[0012] Another exemplary embodiment of the pump is configured as a
roller cell pump. Here, the delivery elements are configured as
rollers which are received displaceably, as viewed in the radial
direction, in corresponding shaped receptacle cut-outs of the
rotor. In this case, the rollers preferably run on an inner
circumferential face of a contour ring, in which the rotor is
arranged. The function of the roller cell pump is otherwise
identical to the function of a vane cell pump, with the result that
reference is made to the description of the latter.
[0013] It is possible that the pump has only one pump section with
a pressure space and a suction space. In this case, the pressure
region is preferably fluidically connected to the expelling regions
which, as viewed in the circumferential direction, are arranged at
the level of the suction region. This ensures that, during starting
of the pump, the delivery elements in the suction region are
displaced against the contour ring, with the result that the
suction function of the pump is ensured from the start.
[0014] One exemplary embodiment of the pump is also preferred, in
which said pump is of double-flow configuration. In this case, the
pump comprises two pump sections, a first pump section having a
first pressure region and a first suction region which is assigned
to it, and a second pump section having a second suction region and
a second pressure region which is assigned to it. Here, a fluidic
connection is preferably provided from the first pressure region to
expelling regions which, as viewed in the circumferential
direction, are arranged at the level of the second suction region.
Here, in the case of a correct installation of the pump, the first
pressure region is preferably arranged so as to lie at the bottom.
The fact that the second suction region which trails the first
pressure region, as viewed in the rotational direction of the
rotor, is supplied with fluid during starting of the pump in the
expelling region which is assigned to it ensures that the second
pump section which lies at the top can also produce a delivery
output as it were from the start of the pump.
[0015] It is possible that a fluidic connection is provided between
the second pressure region and expelling regions which, as viewed
in the circumferential direction, are arranged at the level of the
first suction region. As an alternative, it is preferably possible
that the expelling regions at the level of the first suction region
are also fluidically connected to the first pressure region, the
second pressure region preferably not being fluidically connected
to expelling regions in this case. In particular, the pump is
preferably configured in such a way that the pump section which
lies at the bottom in the case of installation as intended supplies
the expelling regions of the suction region of the pump section
which lies at the top with pressurized fluid, in order to drive the
delivery elements which are retracted in the top pump section at a
standstill into their functional position. In addition, it is
possible that the first pressure region is also fluidically
connected to expelling regions of the first suction region which is
assigned to it. In its first functional position, the cold starting
element preferably also shuts off a fluidic connection between the
first and the second pressure region.
[0016] A pump is preferred which is distinguished by the fact that
the cold starting element is configured as a cold starting plate.
In this case, in its first functional position, the cold starting
plate preferably covers at least one pressure region, with the
result that the latter is not in fluidic connection with the
pressure space. A fluidic connection between the two pressure
regions of a pump of double-flow configuration is also preferably
interrupted by way of the cold starting plate when the cold
starting plate is arranged in its first functional position. In one
exemplary embodiment, in which only one pressure region is
fluidically connected to expelling regions, it is sufficient if the
cold starting plate covers said pressure region and interrupts its
connection to a second pressure region which is not fluidically
connected to expelling regions.
[0017] The cold starting element, in particular the cold starting
plate, is preferably prestressed into its first functional position
by way of a spring element. The spring element is preferably
configured as a helical spring.
[0018] It is provided in an alternative exemplary embodiment of the
pump that the cold starting element comprises at least one cold
starting valve insert. If the pump has two pump sections, each pump
section is preferably assigned a separate cold starting valve
insert. In an exemplary embodiment of this type, the relief face is
preferably arranged on a piston of the cold starting valve insert,
with the result that the piston is pressure-relieved.
[0019] A pump is also preferred which is distinguished by the fact
that the relief receptacle is configured as a bore. The bore is
preferably arranged in a housing of the pump. In this way, a
compact arrangement of the relief receptacle and therefore also of
the relief face which saves installation space is possible. In
particular, no separate element is required as a result of the
integration of the relief receptacle into the pump housing.
[0020] A pump is also preferred which is distinguished by the fact
that a relief bore opens into the relief receptacle. Said relief
bore is fluidically connected to the surrounding region of the pump
or to a reservoir for fluid which is delivered by the pump. The
relief receptacle is pressure-relieved by way of the relief bore.
If the relief bore is fluidically connected to the surrounding
region of the pump, ambient pressure, preferably atmospheric
pressure, prevails in the region of the relief bore and therefore
also in the region of the relief receptacle. It is clear that the
pressure, with which the relief face is loaded, is smaller in this
case than the system pressure of the pump in the outflow region. As
an alternative or in addition, it is provided that the relief bore
is fluidically connected to a reservoir for fluid which is
delivered by the pump. Here, the pump delivers the fluid from the
reservoir to a consumer, from which it preferably runs back into
the reservoir again. Here, with or by way of the consumer, the pump
generates a pressure difference between the reservoir and the
outflow region which is fluidically connected to the consumer. To
this extent, there is always a pressure in the reservoir, which
pressure is lower than the system pressure which is predefined by
the consumer in the outflow region. The relief face is therefore
also loaded in this case with the pressure which is lower during
operation of the pump than the system pressure in the outflow
region. The reservoir is preferably of pressureless configuration,
with the result that atmospheric pressure or ambient pressure also
prevails here. This is the case, in particular, when the reservoir
is ventilated toward the surrounding region.
[0021] A pump is also preferred, in which the relief receptacle is
of cylindrical configuration. The relief receptacle is particularly
preferably configured as a cylindrical bore, in particular in the
housing of the pump. Here, the relief receptacle is particularly
preferably of circularly cylindrical configuration, in particular
is configured as a circularly cylindrical bore.
[0022] A pump is also preferred which is distinguished by the fact
that the relief receptacle has an axial bottom face. Here, the term
"bottom face" addresses a face which is oriented substantially
perpendicularly, preferably precisely perpendicularly, with respect
to the rotational axis of the pump, said face delimiting the relief
receptacle, as viewed in the axial direction.
[0023] In principle, an axial direction is to be understood to mean
a direction which is oriented along the rotational axis of the
pump. The circumferential direction is a direction which reaches
around the rotational axis concentrically. A radial direction is a
direction which lies perpendicularly on the rotational axis.
[0024] The relief bore preferably opens into the bottom face. The
relief face is preferably arranged in the first functional position
at a first spacing and in the second functional position at a
second spacing from the bottom face. Here, the second spacing is
smaller than the first spacing. Accordingly, the relief face is
displaced towards the bottom face when the cold starting element is
displaced from its first functional position into the second
functional position. In one exemplary embodiment of the pump, the
relief face bears against the axial bottom face in the second
functional position.
[0025] One exemplary embodiment of the pump is also preferred, in
which the relief receptacle has an axial end face on a wall which
reaches around it. The axial end face is preferably configured as
an annular face. A first sealing element is arranged on the axial
end face, against which first sealing element the cold starting
element bears sealingly with a rear face in the second functional
position. The end face is preferably oriented perpendicularly with
respect to the rotational axis. Correspondingly, the rear face of
the cold starting element is preferably also oriented
perpendicularly with respect to the rotational axis. The first
sealing element extends in the circumferential direction along the
end face, with the result that the rear face can bear sealingly
against it in the second functional position. As a result, an
internal volume of the relief receptacle which is fluidically
connected to the relief bore is sealed with respect to the pressure
space, with the result that the system pressure acts merely on the
remaining rear face, whereas the relief face which is arranged in
the region of the relief receptacle is loaded with the pressure
which prevails in the relief bore or the relief receptacle and is
lower than the system pressure. The first sealing element is
preferably configured as an O-ring. It is possible that a groove,
in particular an annular groove, is made in the end face, in which
groove the first sealing element is received. The first sealing
element and preferably the annular groove, in which it is arranged,
are preferably arranged concentrically with respect to the
rotational axis of the pump.
[0026] A pump is preferred which is distinguished by the fact that
the cold starting element has a relief projection on its side which
faces away from the pressure region, on which relief projection the
relief face is arranged. Here, the relief projection is guided
displaceably in the relief receptacle. Starting from the rear face
of the cold starting element, the relief projection preferably
extends substantially in the direction of the rotational axis away
from the pressure region into the relief receptacle. The relief
face is preferably configured on the relief projection as an axial
end face which faces away from the pressure region and is oriented
perpendicularly with respect to the rotational axis.
[0027] In one preferred exemplary embodiment, the relief projection
has a cross-sectional geometry which corresponds to the
cross-sectional geometry of the relief receptacle. In one preferred
exemplary embodiment, both the relief projection and the relief
receptacle are of cylinder-symmetrical, in particular circularly
cylindrical configuration. Other suitable designs are also
possible, in which the relief projection is guided displaceably in
the relief receptacle.
[0028] In this context, one exemplary embodiment of the pump is
preferred, in which the relief projection is guided with play in
the relief receptacle. This means, in particular, that a greatest
external diameter of the relief projection is at least slightly
smaller than a smallest external diameter of the relief receptacle.
This design has the advantage that friction forces between the wall
of the relief receptacle and an outer circumferential face of the
relief projection are reduced. However, the clearance fit is
preferably configured in such a way that sufficient guidance of the
relief projection in the relief receptacle still results, so that
there is no jamming of the relief projection in the relief
receptacle during the displacement of the cold starting element
from the first into the second functional position or vice
versa.
[0029] One exemplary embodiment of the pump is also preferred, in
which the relief projection is of spherical configuration. In this
case, as viewed in the direction of the rotational axis, it has a
varying external diameter which, starting from the rear face,
increases first of all as far as a region of the greatest diameter,
said relief projection decreasing in size again, starting from said
region of greatest diameter, towards the relief face. By way of the
region of greatest external diameter, the relief projection is
centred and guided in the relief receptacle. In the case of
possible tilting and/or angled positioning with respect to the
rotational axis, jamming of the cold starting element during its
stroke from the first into the second functional position or vice
versa is prevented effectively by way of the spherical shape of the
relief projection. At the same time, friction between the relief
projection and the relief receptacle is reduced because there is
contact merely in the region of the greatest external diameter.
[0030] One exemplary embodiment of the pump is also preferred which
is distinguished by the fact that the relief face which is arranged
on the relief projection is reached around by a second sealing
element, with which the relief projection bears sealingly against
the axial bottom face in the second functional position. The second
sealing element is preferably configured as an O-ring or as a
shaped seal. The numbering of the sealing elements, for example, as
first and second sealing element in no way means that all the
sealing elements which are mentioned here and in the following text
necessarily have to be provided in each exemplary embodiment.
Rather, the numbering of the sealing elements serves merely to
distinguish them theoretically. An exemplary embodiment of the pump
is therefore possible which has only the first sealing element. An
exemplary embodiment of the pump is also possible which has only
the second sealing element. However, an exemplary embodiment of the
pump is also possible which has both the first and the second
sealing element.
[0031] The second sealing element is preferably fastened captively
to the relief projection in the region of the relief face. Here, as
viewed in the axial direction, it protrudes beyond the relief face
towards the axial bottom face at least to such an extent that its
sealing contact with said axial bottom face is ensured in the
second functional position of the cold starting element. In one
preferred exemplary embodiment, it is configured in such a way
that, as viewed in the radial direction, it is at a sufficient
spacing from the wall of the relief receptacle, with the result
that no additional friction forces are generated by way of the
second sealing element during the stroke of the cold starting
element, which additional friction forces might impede a movement
of the cold starting element.
[0032] An exemplary embodiment of this type can be realized in a
particularly suitable manner if the relief projection is of
spherical configuration. In this case, an external diameter of the
relief projection in the region of the relief face is smaller
anyway than the greatest external diameter which interacts with the
wall of the relief receptacle. It is therefore readily possible to
arrange the second sealing element in the region of the relief face
in such a way that it does not come into contact with the wall of
the relief receptacle.
[0033] As soon as the cold starting element has reached its second
functional position, the second sealing element bears sealingly
against the axial bottom face. Here, as viewed in the radial
direction, the relief bore is arranged within the second sealing
element, with the result that the region of the relief face
radially within the second sealing element after the sealing
contact of the latter against the axial bottom face is loaded with
the pressure which is lower with regard to the system pressure, as
a result of which the cold starting element overall is
relieved.
[0034] In a reversal of this functional principle, it is also
possible that the second sealing element is provided on the axial
bottom face. In this case, it is preferably arranged in a groove
which is provided in the axial bottom face, in particular an
annular groove, said second sealing element preferably being
configured as a O-ring. In the second functional position of the
cold starting element, the relief face bears sealingly against the
second sealing element.
[0035] One exemplary embodiment of the pump is also preferred, in
which a third sealing element is arranged on the relief projection,
which third sealing element reaches around the relief projection,
as viewed along its circumference. Here, the third sealing element
bears sealingly against the wall which reaches around the relief
receptacle. The third sealing element is preferably configured as
an O-ring. In one preferred exemplary embodiment, the relief
projection has a groove in its outer circumferential face, in
particular an annular groove, in which the third sealing element is
arranged.
[0036] The numbering of the sealing element as "third sealing
element" also serves merely in this case to distinguish it
theoretically from the first and the second sealing element. It is
in no way necessarily provided that one exemplary embodiment has
all three sealing elements.
[0037] Radial sealing of the relief receptacle is achieved by way
of the third sealing element, whereas axial sealing is achieved by
way of the first and/or the second sealing element. In every
functional position of the cold starting element, the third sealing
element bears sealingly against the wall of the relief receptacle.
A leakage path during the opening stroke of the cold starting
element, as long as the latter is not yet arranged in its second
functional position, is therefore avoided with the aid of the third
sealing element. The relief projection can be of short and compact
configuration. However, the sealing element which is arranged in
the region of the circumference of the relief projection increases
the friction which acts during the stroke, with the result that an
increased application of force is required for displacing the cold
starting element from its first functional position into its second
functional position. A short overall design of the relief
projection and the relief receptacle has the disadvantage,
moreover, that jamming of the cold starting element can occur
during the stroke.
[0038] One exemplary embodiment of the pump is also preferred, in
which the relief projection is guided substantially without play in
the relief receptacle. In this case, the external diameter of the
relief projection and the internal diameter of the wall of the
relief bore are manufactured with an accurate fit with respect to
one another, which results here in only a small, minimum play.
Jamming of the relief projection in the relief receptacle is
virtually ruled out as a result of the substantially play-free
guidance, a relative movement between the elements still being
possible at the same time, however. Accordingly, the wording
"substantially play-free" addresses the fact that there is firstly
tight guidance with avoidance of jamming and secondly also at the
same time displaceability between the elements. In this case, the
length of the relief projection and the relief receptacle are
preferably selected in such a way that a leakage towards the relief
bore on account of the substantially play-free guidance is so low
that an additional seal can be dispensed with. In this case,
preferably neither the first nor the second nor the third sealing
element is therefore required. However, an increased installation
space requirement results on account of the axial extension of the
relief projection which is necessary for a sufficient sealing
action. In addition, a leakage path which is permanent if small
remains between the relief projection and the relief receptacle
towards the relief bore.
[0039] One exemplary embodiment is preferred, in which the relief
projection has at least one pressure relief groove which extends in
the circumferential direction on a circumferential face. In a
manner which is known per se, radial forces in the region of the
relief projection are to be avoided by way of a pressure relief
groove of this type, because the pressure on all sides around the
relief projection can be equalized via the pressure relief groove.
The relief projection is therefore centred by way of the at least
one pressure relief groove. This is a customary design of pistons
which are guided substantially without play, and is known per se,
with the result that it is not described in further detail
here.
[0040] It is nevertheless possible, in one exemplary embodiment, in
which the relief projection is guided at least virtually without
play in the relief receptacle, to provide an axial seal in the form
of the first sealing element and/or in the form of the second
sealing element. In this case, the play of the relief projection in
the relief receptacle can be increased at least to such an extent
that pressure relief grooves are not required for centring the
relief projection. The leakage which is increased per se as a
result is then reduced by way of the axial seal in the form of the
first and/or the second sealing element in the second functional
position of the cold starting element.
[0041] One exemplary embodiment of the pump is also preferred, in
which the cold starting element overall is configured as a piston
which is guided in regions in the relief receptacle. In an
exemplary embodiment of this type, the cold starting element does
not have a relief projection, but rather is itself overall
configured as a piston with an outer circumferential face which is
guided in the relief receptacle. In this way, a particularly short
overall design of the cold starting element can be realized, and
the relief face is configured to be very large in comparison with
the entire face of the cold starting element which faces away from
the pressure region. In particular, the relief face comprises
virtually the entire face of the cold starting element which faces
away from the pressure region. As a result, said cold starting
element is pressure-relieved particularly efficiently. In an
exemplary embodiment of this type, however, there is an increased
installation space requirement in the radial direction because the
relief receptacle has to be adapted to the entire circumference of
the cold starting element.
[0042] It is possible that the cold starting element overall is of
spherical configuration in the region of its outer circumference.
Jamming during an opening stroke from the first functional position
into the second functional position, and also during a closing
stroke from the second functional position into the first
functional position, is avoided as a result. At the same time,
friction forces are reduced.
[0043] One exemplary embodiment is also preferred which is
distinguished by the fact that a fourth sealing element is arranged
on a stop face of the cold starting element, which stop face faces
the axial bottom face. This design is preferred if the cold
starting element overall is configured as a piston which is guided
in regions in the relief receptacle. The cold starting element
bears sealingly against the bottom face with the fourth sealing
element here in the second functional position.
[0044] The fourth sealing element is preferably configured as an
O-ring. A groove, in particular an annular groove, is particularly
preferably made in the stop face, in which groove the fourth
sealing element is arranged.
[0045] The designation of the fourth sealing element in the context
of numbering also serves in this case merely to distinguish the
different sealing elements theoretically. It is in no way
necessarily provided that each exemplary embodiment of the pump
comprises all the sealing elements.
[0046] In the exemplary embodiment of the pump, in which the cold
starting element overall is configured as a piston which is guided
in regions in the relief receptacle, the spring element is
preferably arranged in regions in a cut-out of the cold starting
element, said spring element being supported on the rear face of
the cold starting element, which rear face is part of the relief
face here.
DRAWINGS
[0047] The drawings described herein are for purposes of
illustration only of selected embodiments and not all possible
implementations, and the drawings are not intended to limit the
scope of the present disclosure.
[0048] In the following text, the disclosure will be explained in
greater detail using the drawings, in which:
[0049] FIG. 1 shows a diagrammatic illustration of a first
exemplary embodiment of the pump having a cold starting element in
the first functional position,
[0050] FIG. 2 shows a diagrammatic illustration of the first
exemplary embodiment of the pump having the cold starting element
in the second functional position,
[0051] FIG. 3 shows a diagrammatic illustration of a second
exemplary embodiment of the pump,
[0052] FIG. 4 shows a diagrammatic detailed illustration of a third
exemplary embodiment of the pump,
[0053] FIG. 5 shows a diagrammatic detailed illustration of a
fourth exemplary embodiment of the pump, and
[0054] FIG. 6 shows a diagrammatic illustration of a fifth
exemplary embodiment of the pump.
DETAILED DESCRIPTION
[0055] Example embodiments will now be more fully described with
reference to the accompanying drawings. However, the following
description is merely exemplary in nature and is not intended to
limit to present disclosure; its subject matter, applications or
uses.
[0056] Example embodiments are provided so that this disclosure
will be thorough, and will fully convey the scope to those who are
skilled in the art. Numerous specific details are set forth such as
examples of specific components, devices, and methods, to provide a
thorough understanding of embodiments in many different forms and
that neither should be construed to limit the scope of the
disclosure. In some example embodiments, well-known processes,
well-known device structures, and well-known technologies are not
described in detail.
[0057] FIG. 1 shows a diagrammatic illustration of a part detail of
a first exemplary embodiment of a pump 1 which is configured here
as a vane cell pump. The pump 1 has a housing 3, in which a pump
assembly 5 is received. Said pump assembly 5 comprises a rotor 7
which is connected fixedly to a shaft 9 so as to rotate with it,
which shaft 9 can be rotated about a rotational axis A. The rotor 7
has radially running receptacles which are configured here as slots
and in which delivery elements 11 are received displaceably, as
viewed in the radial direction, that is to say perpendicularly with
respect to the rotational axis A.
[0058] Moreover, the rotor 7 comprises expelling regions 13
radially within the delivery elements 11, that is to say as viewed
in the direction towards the rotational axis A, which expelling
regions 13 can be loaded with a pump pressure during operation of
the pump 1 by way of lower delivery element grooves 14 which are
fluidically connected to the expelling regions 13, with the result
that the delivery elements 11 are expelled out of the receptacles
not only by way of the centrifugal force on account of the rotation
of the rotor 7 about the rotational axis A, but also by way of the
pressure force which acts on them in the radial direction in the
outlet regions 13. Here, the delivery elements 11 are displaced
against an inner circumferential face 15 of a contour ring 17. Said
inner circumferential face 15 is configured in such a way that at
least one, preferably two, particularly preferably crescent-shaped
delivery spaces are formed. Said delivery spaces are passed through
by the delivery elements 11, two pump sections with in each case
one suction region (not shown) and in each case one pressure region
19, 19' (shown in FIG. 1) being formed. The pressure regions 19,
19' are configured, for example, as pressure kidneys in a pressure
plate 21. At least one of the pressure regions 19, 19', in specific
terms only the low pressure region 19 here, is fluidically
connected at least in regions to the expelling regions 13 via a
first fluid path 20 which is formed by way of the lower delivery
element grooves 14, with the result that said expelling regions 13
are loaded during operation of the pump 1 at least in regions, in
particular dependent on an instantaneous rotary angle of the rotor
7, with the pump pressure which prevails in the pressure region
19.
[0059] The rotor 7 and the contour ring 17 bear sealingly on the
axial front side 8, 18 thereof against a sealing face (not shown
here) of the housing 3. The pressure plate 21 is provided on an
opposite side (as viewed in the axial direction) of said two parts,
which pressure plate 21 has the pressure regions 19, 19' as
recesses, for example as what are known as pressure kidneys, and by
way of which pressure plate 21 the fluid which is delivered by the
pump 1 is guided during operation of the pump 1 into a pressure
space 23, said pressure space 23 having an outflow region 25,
through which the fluid is guided to a consumer. The pressure plate
21 is preferably supported by a housing collar 22 against the
contour ring 17 and the rotor 7. The pressure plate 21 is sealed
against the housing 3, for example, by way of a radial sealing
element 27 which is preferably configured as an O-ring. The lower
delivery element grooves 14 which are configured as lower vane
groups in the exemplary embodiment of the vane cell pump which is
shown are made in the pressure plate 21. The lower delivery element
grooves 14 are fluidically connected firstly to the pressure region
19 and secondly at least in regions to the expelling regions
13.
[0060] The pump 1 has a cold starting device 29 which comprises a
cold starting element 31 which is prestressed into a first
functional position shown in FIG. 1 and is configured here as a
cold starting plate 33. A second fluid path 35 which is symbolized
by way of arrows in FIG. 2 and leads from the pressure regions 19,
19' to the pressure space 23 is shut off in the first functional
position (shown in FIG. 1) of the cold starting element 31. At the
same time, the first fluid path 20 is also shut off or sealed with
respect to the pressure space 23. Here, in the exemplary embodiment
which is shown, the cold starting element 31 or the cold starting
plate 33 lies with a sealing face 37 sealingly on the pressure
plate 21, with the result that the pressure regions 19, 19' are
closed sealingly with respect to the pressure space 23. In the
exemplary embodiment which is shown, in which only one of the
pressure regions 19, 19', namely the pressure region 19 here, is
fluidically connected to the expelling regions 13, it is sufficient
in principle if the cold starting element 31 sealingly closes said
one pressure region 19 and at the same time also the first fluid
path 20 towards the pressure space 23.
[0061] In the exemplary embodiment which is shown, in its first
functional position, the cold starting plate 33 also disconnects a
fluidic connection between the two pressure regions 19, 19'
completely.
[0062] In the exemplary embodiment which is shown, the cold
starting plate 33 is displaced into its first functional position
and therefore against the pressure plate 21 by way of a spring
element 39 which is configured here as a helical spring 41. Said
cold starting plate 33 is accordingly prestressed into the first
functional position by way of the spring element 39. Here, the
helical spring 41 is supported on one side on the housing 3, in
particular on a supporting shoulder 43 there, and on the other side
on a rear face 45 of the cold starting element 31. Here, the rear
face 45 faces away from the pressure regions 19, 19' and faces the
pressure space 23. It extends perpendicularly with respect to the
rotational axis A here.
[0063] The function of the cold starting device 29 is as follows:
when the pump 1 is brought to a standstill, the delivery elements
11 which are arranged at the top in FIG. 1 move as a result of
gravity into the receptacles of the rotor 7, and therefore into the
expelling regions 13. When the pump becomes colder, the viscosity
of fluid which is delivered by the pump 1, for example a hydraulic
oil, increases. When the pump 1 is started up again, a
short-circuit between the suction region and the top pressure
region 19' results in a region which is arranged at the top, in
which the delivery elements 11 have retracted into the rotor 7, the
delivery elements 11 extending out of the rotor 7 only slowly
solely as a result of gravity, because they can be moved only
slightly in the viscous, cold fluid. The pump 1 therefore requires
a relatively long starting-up time and/or a high rotational speed
before it exhibits its full delivery capacity.
[0064] This problem is eliminated by way of the cold starting
device 29. At the standstill of the pump, the pressure space 23 is
pressureless. The cold starting element 31 is displaced against the
pressure plate 21 by the spring element 39 and thus seals the
pressure regions 19, 19' with respect to the pressure space 23 and
preferably also with respect to one another. When the pump 1 then
runs up, first of all no fluid is delivered via the pressure
regions 19, 19' into the pressure space 23. Rather, all the fluid
which is delivered by the lower pressure space 19 passes via the
first fluid path 20 into the expelling regions 13, with the result
that the delivery elements 11 are expelled by way of the fluid
which is delivered by the pump 1 during running up and by way of
the pressure which is produced in this way. The pump 1 therefore
exhibits its full delivery capacity very rapidly. If the pressure
in the pressure regions 19, 19' correspondingly rises above a
value, at which the force which acts on the cold starting element
31 counter to the spring force of the spring element 39 is greater
than said prestressing force, the cold starting element 31 is
displaced to the right (in FIG. 1), with the result that it
releases the second fluid path 35. The pump then delivers fluid via
the pressure regions 19, 19' into the pressure space 23 and via the
outflow region 25 further to the consumer (not shown here). Here, a
system pressure which depends, inter alia, on the consumer prevails
in the pressure space 23. The system pressure also loads the rear
face 45 of the cold starting plate 33. The pump pressure which
prevails in the pressure regions 19, 19' therefore has to be great
enough, in order to hold the cold starting element 31 in the second
functional position, and therefore open, permanently during
operation of the pump counter to the prestress of the spring
element 39 firstly and the system pressure secondly. Accordingly,
the pump has an increased power consumption solely by virtue of the
fact that the cold starting element 31 has to be held open
permanently.
[0065] This problem is solved by way of the pump 1 which is
proposed here. To this end, it is provided that the cold starting
element 31 has a relief face 47 which faces away from the pressure
regions 19, 19' and by way of which it is arranged in a relief
receptacle 49. Said relief receptacle 49 is configured as a bore in
the housing 3 in the exemplary embodiment which is shown in FIG.
1.
[0066] It is shown, moreover, that the cold starting element 31 has
a relief projection 51 here on its side which faces away from the
pressure regions 19, 19', namely starting from the rear face 45, on
which relief projection 51 the relief face 47 is arranged as an
axial end face. The relief projection 51 extends in the direction
of the rotational axis A, starting from the rear face 45, away from
the pressure regions 19, 19' into the relief receptacle 49. Here,
the relief face 47 is oriented in such a way that the rotational
axis A lies perpendicularly on it.
[0067] The relief projection 51 preferably has narrow tolerances in
the relief receptacle 49. In the exemplary embodiment which is
shown in FIG. 1, it is of spherical configuration, that is to say
has a region 53 of greatest diameter which is spaced apart firstly
from the rear face 45 and secondly from the relief face 47, in each
case as viewed in the axial direction. The spherical design of the
relief projection 51 ensures that it does not jam in the relief
receptacle 49 during a stroke of the cold starting element 31, even
in the case of slight tilting movements. Otherwise, the relief
projection 51 is preferably configured symmetrically with respect
to the rotational axis A.
[0068] The relief receptacle 49 has a wall 55 which is configured
as an inner circumferential wall. Said wall 55 is of
cylinder-symmetrical configuration and, with regard to its internal
diameter, is adapted to the external diameter, in this case to the
greatest external diameter of the relief projection 51, in such a
way that said relief projection 51 has narrow tolerances in the
relief receptacle 49 and, in particular, is guided with or
substantially without play, that is to say with minimum play,
depending on the exemplary embodiment.
[0069] A relief bore 57 opens into the relief receptacle 49, which
relief bore 57 is fluidically connected in a manner which is not
shown here to a surrounding region of the pump 1 or to a reservoir
for fluid which is delivered by the pump 1. The relief receptacle
49 is therefore pressure-relieved by the relief bore 57 and always
has the ambient pressure or reservoir pressure which is lower in
comparison with the system pressure during operation of the pump
1.
[0070] Moreover, the relief receptacle 49 has an axial bottom face
59, into which the relief bore 57 opens. In this case, the axial
bottom face 59 extends here perpendicularly with respect to the
rotational axis A. The axial bottom face 59 is oriented parallel to
the relief face 47. Here, in the first functional position of the
cold starting element 31 which is shown in FIG. 1, the relief face
47 is arranged at a first spacing d.sub.1 from the axial bottom
face 59.
[0071] The relief face 47 which is arranged on the relief
projection 51 is reached around by a second sealing element 61. The
sealing element 61 is preferably configured as an O-ring or as a
shaped seal. One exemplary embodiment of the pump 1 is also
possible, in which the sealing element 61 is not provided, the
exemplary embodiment otherwise being configured as shown in FIG. 1.
The sealing element 61 serves, when bearing against the axial
bottom face 59, to stop a leakage flow between the relief
projection 51 and the wall 55 towards the relief bore 57. If a
leakage of this type which is possibly present is accepted or is
minimized by way of corresponding tolerances of the components, it
is possible to dispense with the sealing element 61.
[0072] The sealing element 61 is preferably fastened captively to
the relief projection 51 in the region of the relief face 47. It is
configured here in such a way that it is at a sufficient radial
spacing from the wall 55, in order not to generate any additional
friction forces in the region of the wall 55 during an opening
stroke or else during a closing stroke of the cold starting element
31. At the same time, the sealing element 61 protrudes beyond the
relief face 47, as viewed in the axial direction, towards the axial
bottom face 59, with the result that its resilient, elastic and
sealing contact with the axial bottom face 59 is possible.
[0073] FIG. 2 shows the exemplary embodiment of the pump 1
according to FIG. 1 in the second functional position of the cold
starting element 31. Identical and functionally identical elements
are provided with identical reference numerals, with the result
that reference is made to this extent to the preceding description.
On account of the pump pressure which prevails in the pump spaces
19, 19' during operation of the pump 1, the cold starting element
31 is displaced counter to the prestressing force of the spring
element 39 into the second functional position. Here, the second
fluid path 35 is released, with the result that the fluid which is
delivered by the pump 1 is delivered by way of the pressure regions
19, 19' into the pressure space 23 and via the outflow region 25
(as indicated by an arrow P) to a consumer (not shown).
[0074] In the second functional position, the relief face 47 is
arranged at a second spacing d.sub.2 from the bottom face 59, the
second spacing d.sub.2 being equal to or approximately zero in the
exemplary embodiment which is shown, with the result that the
relief face 47 substantially bears against the axial bottom face 59
here (apart from the spacing which is defined by way of the
compressed sealing element 61). The second sealing element 61 which
protrudes somewhat beyond the relief face 47 is namely compressed,
said second sealing element 61 bearing sealingly against the axial
bottom face 59. Leaks which possibly exist between the relief
projection 51 and the wall 55 are sealed in this way, with the
result that no fluid can escape from the pressure space 23 through
the relief bore 57. As has already been described, it is possible
in the case of corresponding tolerances of the components and/or an
acceptance of a low leakage to dispense with the second sealing
element 61. An exemplary embodiment of this type of the pump 1 is
then particularly inexpensive.
[0075] It is shown that, in its second functional position, the
cold starting element 31 is arranged at least in regions with the
relief face 47 which faces away from the pressure region 19, 19' in
the relief receptacle 49 in such a way that the relief face 47 is
loaded during operation of the pump 1 with a pressure which is
smaller than the system pressure in the outflow region 25.
[0076] The region which is arranged radially inside the second
sealing element 61, in particular the relief face 47, is namely
pressure-relieved by way of the relief bore 57, with the result
that the system pressure does not load the cold starting element 31
here, but rather the lower pressure in the relief bore 57,
preferably the ambient pressure or the pressure in a reservoir for
the fluid which is delivered by the pump 1. As a result, the forces
which are required to hold the cold starting element 31 open are
reduced in the region of the pressure regions 19, 19', with the
result that the difference between the pump pressure in said
regions and the system pressure in the pressure space 23 or in the
outflow region 25 is reduced. The power consumption of the pump 1
is reduced as a result.
[0077] During the opening stroke of the cold starting plate 33, a
small leakage path to the relief bore 57 results at any rate until
the second sealing element 61 bears sealingly against the axial
bottom face 59. The temporary, brief leakage is comparatively
small, however, and can be accepted readily.
[0078] It is also shown that the prestressing force of the spring
element 39 is preferably adapted to the specific requirements of
the pump 1, in particular to the lowermost pressure level which is
necessary to expel the delivery elements 11. Via the prestress of
the spring element 39, the opening pressure of the cold starting
element 31 is namely fixed, and therefore the lowest pump-internal
pressure, at which the pump 1 delivers fluid.
[0079] The exemplary embodiment according to FIGS. 1 and 2 has a
compact overall design which is short, in particular, as measured
in the axial direction, jamming of the relief projection 51 in the
relief receptacle 49 during the opening stroke and/or during a
closing stroke in the case of possible tilting movements and/or
axial angular errors between the cold starting element 31 and the
relief receptacle 49 not being possible as a result of the
spherical shape of said relief projection 51.
[0080] FIG. 3 shows a diagrammatic illustration of a second
exemplary embodiment of the pump 1. Identical and functionally
identical elements are provided with identical reference numerals,
with the result that reference is made to the preceding description
to this extent. The exemplary embodiment according to FIG. 3
differs from the first exemplary embodiment according to FIGS. 1
and 2 merely in so far as the relief receptacle 49 is sealed
differently in the second functional position of the cold starting
element 31. In the following text, merely the differences between
the exemplary embodiments will be described.
[0081] In the second exemplary embodiment which is shown in FIG. 3,
the relief receptacle 49 comprises an end face 63 which is
configured as an annular face and reaches around the relief
receptacle 49 on the wall 55. Said end face 63 is also provided per
se in the first exemplary embodiment according to FIGS. 1 and 2 and
is labelled correspondingly there. In a difference from the first
exemplary embodiment, however, the second exemplary embodiment
according to FIG. 3 has a first sealing element 65 which is
arranged on the end face 63. A groove, in particular an annular
groove, is preferably provided in the end face 63, in which groove
the first sealing element 65 which is preferably configured as an
O-ring is received in regions. The cold starting element 31 (the
cold starting plate 33 here) bears sealingly with the rear face 45
on the first sealing element 63 in the second functional position.
In this way, an interior 67 of the relief receptacle 49 is sealed
with respect to the pressure space 23 and the outflow region 25.
The entire interior 67 of the relief receptacle 49 is therefore
pressure-relieved via the relief bore 57 in the second exemplary
embodiment.
[0082] Otherwise, the same advantages which have already been
explained in conjunction with the first exemplary embodiment and
FIGS. 1 and 2 are realized with regard to the second exemplary
embodiment according to FIG. 3. In particular, the exemplary
embodiment according to FIG. 3 also has a compact overall design
which is short as viewed in the axial direction. Jamming of the
cold starting element 31 during the opening stroke and/or during
the closing stroke is avoided effectively by way of the spherical
design of the relief projection 51.
[0083] FIG. 4 shows a diagrammatic detailed illustration of a third
exemplary embodiment of the pump 1. Identical and functionally
identical elements are provided with identical reference numerals,
with the result that reference is made to this extent to the
preceding description. Even in conjunction with FIG. 4, merely the
differences from the previously described exemplary embodiments are
explained, with the result that reference is otherwise made to the
preceding description.
[0084] In the third exemplary embodiment, a third sealing element
69 which reaches around the relief projection 51 along its
circumference is arranged on the relief projection 51. Here, the
third sealing element 69 bears sealingly against the wall 55 which
reaches around the relief receptacle 49. In this exemplary
embodiment, this applies to each functional position of the cold
starting element 31 (specifically, the cold starting plate 33
here). In this way, an additional leakage path between the relief
projection 51 and the wall 55 towards the relief bore 57 is always
avoided independently of the instantaneous functional position of
the cold starting element 31, with the result that a leakage flow
via the relief bore 57 does not occur at any time. At the same
time, however, friction between the relief projection 51 and the
wall 55 is increased by way of the third sealing element 69 which
bears sealingly against the wall 55, with the result that a
slightly increased pump pressure in comparison with the previously
described exemplary embodiments is required, in order to displace
the cold starting element 31 from its first into its second
functional position. However, this can also be compensated for by
way of the use of a spring element 39 (not shown in FIG. 4) which
is adapted correspondingly with regard to its prestressing force.
Here, however, the spring element 39 also has to have a sufficient
prestressing force, in order to displace the cold starting element
31 in the pressureless state counter to friction forces back into
its first functional position.
[0085] In the third exemplary embodiment, it is preferably provided
that the relief projection 51 is of cylindrical configuration, in
particular is configured as a circular cylinder, said relief
projection 51 having an outer circumferential face 71. The relief
receptacle 49 is preferably likewise of cylindrical, in particular
circularly cylindrical, configuration, the wall 55 defining an
inner circular cylinder, in which the relief projection 51 which is
configured as an outer circular cylinder is guided. A
circumferential (as viewed in the circumferential direction)
annular groove 73 is preferably made in the outer circumferential
face 71, in which annular groove 73 the third sealing element 69
which is preferably configured as an O-ring is arranged.
[0086] The third exemplary embodiment according to FIG. 4 also
requires only a very small installation space, in particular in the
axial direction. It is therefore of very compact configuration.
[0087] FIG. 5 shows a diagrammatic detailed illustration of a
fourth exemplary embodiment of the pump 1. Identical and
functionally identical elements are provided with identical
reference numerals, with the result that reference is made to this
extent to the preceding description. Even in conjunction with FIG.
5, merely the differences from the preceding exemplary embodiments
will be explained in the following text, with the result that
reference is made otherwise to the preceding description.
[0088] In the exemplary embodiment according to FIG. 5, the relief
projection 51 is guided substantially without play, that is to say
without jamming, in the relief receptacle 49. In this case, the
tight radial spacing between the relief projection 51 and the wall
55 results in reliable guidance, with the result that tipping
and/or tilting of the cold starting element 31 (the cold starting
plate 33, in particular, here) is avoided effectively. At the same
time, it is possible to dispense with a seal if the relief
projection 51 firstly and the wall 55 secondly are configured to be
long enough (as viewed in the axial direction), with the result
that there is a hydraulic resistance on account of the tight radial
spacing between the relief projection 51 and the wall 55 over the
entire contact length between said elements, which hydraulic
resistance is great enough that a possibly remaining leakage to the
relief bore 57 can be accepted, or is even negligibly small.
[0089] In order, in the case of narrow tolerances of this type of
the relief projection 51 and the wall 55, to avoid, however, that
radial forces act on the relief projection 51, in particular, as a
result of pressure differences on different sides of said relief
projection 51, the relief projection 51 has at least one pressure
relief groove, preferably a multiplicity of pressure relief
grooves, on its outer circumferential face 71 here, of which
pressure relief grooves only one is labelled with the reference 75
here for the sake of improved clarity. The pressure relief groove
75 is configured as an annular groove which extends along the outer
circumferential face 71, as viewed in the circumferential
direction. A varying pressure (as viewed in the circumferential
direction) is thus compensated for via an equalization flow through
the pressure relief groove 75, with the result that the relief
projection 51 is free from radial forces, said relief projection 51
being centred by way of the pressure relief groove 75.
[0090] The relief projection 51 is preferably likewise of
cylindrical, in particular circularly cylindrical configuration
here. The relief receptacle 49 is likewise preferably of
cylindrical, in particular circularly cylindrical,
configuration.
[0091] One exemplary embodiment is possible which is modified in
comparison with the fourth exemplary embodiment according to FIG. 5
to the extent that the first sealing element 65 is provided here on
the end face 63. In this case, at least in the second functional
position of the cold starting element 31, a leak towards the relief
bore 57 is avoided by way of the sealing contact of the rear face
45 on the first sealing element 65. A play between the relief
projection 51 and the wall 55 can therefore be enlarged in this
exemplary embodiment, at least to such an extent that the pressure
relief grooves 75 can be dispensed with.
[0092] As an alternative, it is also possible to provide the second
sealing element 61 in the region of the relief face 47 or the axial
bottom face 59.
[0093] FIG. 6 shows a diagrammatic detailed illustration of a fifth
exemplary embodiment of the pump 1. Identical and functionally
identical elements are provided with identical reference numerals,
with the result that reference is made to this extent to the
preceding description. Even in relation to FIG. 6, merely the
differences from the preceding exemplary embodiments will be
explained, with the result that otherwise reference is made to
their description.
[0094] In the fifth exemplary embodiment which is shown in FIG. 6,
the cold starting element 31 which is also configured here as a
cold starting plate 33 is configured overall as a piston 77 which
is guided in regions in the relief receptacle 49. This has the
advantage that a very large proportion of an axial end face 79 of
the cold starting element 31, which axial end face 79 faces away
from the pressure regions 19, 19', is pressure-relieved in the
second functional position. Here, the relief face 47 namely
comprises firstly a stop face 81 which faces the bottom face 59 and
is preferably annular, and also the rear face 45 which is then
arranged in a cut-out 83 of the cold starting element 31. The
relief face 47 is therefore of stepped configuration, the stop face
81 and the rear face 45 being arranged offset with respect to one
another, as viewed in the axial direction. The spring element 39
which is configured as a helical spring 41 is arranged in the
cut-out 83 which is produced in this way. Here, said spring element
39 is to this extent also arranged in the relief receptacle 49 and
is supported on one side on the rear face 45 and on the other side
on the axial bottom face 59.
[0095] A fourth sealing element 85 is preferably arranged on the
stop face 81, the cold starting element 31 bearing sealingly
against the axial bottom face 59 in its second functional position
with the fourth sealing element 85 which is preferably configured
as an O-ring. It is preferably provided here that a groove, in
particular an annular groove 87, is made in the stop face 81, in
which groove the fourth sealing element 85 is arranged.
[0096] A cut-out 89, into which the relief bore 57 opens, is
preferably made in the axial bottom face 59. The cut-out 89
preferably extends (as viewed in the radial direction) as far as
the fourth sealing element 85 or is configured with regard to its
extent in such a way that it corresponds completely to the relief
face 47 including the rear face 45 and the stop face 81 which is
arranged radially within the fourth sealing element. In this way,
the entire relief face 47 is pressure-relieved particularly
efficiently because the complete region radially within the fourth
sealing element 85 is pressure-relieved via the cut-out 89 and the
relief bore 57 even in the second functional position when said
fourth sealing element 85 bears sealingly against the axial bottom
face 59.
[0097] The piston 77 is preferably of cylinder-symmetrical, in
particular circularly cylindrical, configuration. In this case, it
has a cylindrical, outer circumferential face 71. The relief
receptacle 49 is also preferably of cylindrical, in particular
circularly cylindrical, configuration.
[0098] One exemplary embodiment is possible, in which the outer
circumferential face 71 (as viewed in cross section) is configured
to be circularly symmetrical but (as viewed in the axial direction)
spherical at least in the region which interacts with the wall 55.
As a result, jamming of the cold starting element 31 or the cold
starting plate 33 which is configured as a piston 77 as a result of
tipping and/or tilting during its stroke can be avoided
effectively.
[0099] The fifth exemplary embodiment which is shown in FIG. 6 has
a particularly short overall design (as viewed in the axial
direction) and is therefore of compact configuration. A further
advantage consists in that, as has already been explained, a larger
relief face 47 is formed, with the result that there is
particularly efficient pressure relief.
[0100] As viewed in the radial direction, however, the piston 77
has a greater extent than the relief projection 51 in the
previously described exemplary embodiments. Therefore, in the
exemplary embodiment which is shown in FIG. 6, the outflow region
25 of the pressure space 23 is preferably arranged obliquely, with
preference perpendicularly with respect to the rotational axis A,
whereas it is preferably arranged substantially parallel to the
rotational axis A in the previously described exemplary
embodiments.
[0101] It is shown overall that the pump 1 exhibits both a
favourable cold starting behaviour and a reduced power consumption
during operation.
[0102] While specific aspects have been described in the
specification and illustrated in the drawings, it will be
understood by those skilled in the art that various changes can be
made and equivalence can be substituted for elements thereof
without departing from the scope of the present teachings, as
defined in the claims. Furthermore, the mixing and matching of
features, elements and/or functions between various aspects of the
present teachings is expressly contemplated herein so that one
skilled in the art will appreciate from the present teachings that
features, elements, components, modules and/or functions of one
aspect of the present teachings can be incorporated into another
aspect as appropriate unless described otherwise above. Moreover,
many modifications can be made to adapt a particular situation,
configuration or material to the present teachings without
departing from the essential scope thereof. Therefore, it can be
intended that the present teachings not be limited to the
particular aspects illustrated by the drawings and described in the
specification as the best mode presently contemplated for carrying
out the present teachings but that the scope of the present
teachings will include many aspects and examples following within
the foregoing description and the appended claims.
LIST OF REFERENCE NUMERALS
[0103] 1 Pump [0104] 3 Housing [0105] 5 Pump assembly [0106] 7
Rotor [0107] 8 Front side [0108] 9 Shaft [0109] 11 Delivery element
[0110] 13 Expelling region [0111] 14 Lower delivery element groove
[0112] 15 Inner circumferential face [0113] 17 Contour ring [0114]
18 Front side [0115] 19 Pressure region [0116] 20 First fluid path
[0117] 21 Pressure plate [0118] 22 Housing collar [0119] 23
Pressure space [0120] 25 Outflow region [0121] 27 Radial sealing
element [0122] 29 Cold starting device [0123] 31 Cold starting
element [0124] 33 Cold starting plate [0125] 35 Second fluid path
[0126] 37 Sealing face [0127] 39 Spring element [0128] 41 Helical
spring [0129] 43 Supporting shoulder [0130] 45 Rear face [0131] 47
Relief face [0132] 49 Relief receptacle [0133] 51 Relief projection
[0134] 53 Region [0135] 55 Wall [0136] 57 Relief bore [0137] 59
Axial bottom face [0138] 61 Second sealing element [0139] 63 End
face [0140] 65 First sealing element [0141] 67 Interior [0142] 69
Third sealing element [0143] 71 Circumferential face [0144] 73
Annular groove [0145] 75 Pressure relief groove [0146] 77 Piston
[0147] 79 End face [0148] 81 Stop face [0149] 83 Cut-out [0150] 85
Fourth sealing element [0151] 87 Annular groove [0152] 89 Cut-out
[0153] A Rotational axis [0154] 19' Pressure region [0155] d.sub.1
First spacing [0156] d.sub.2 Second spacing [0157] P Arrow
* * * * *